Dal Lake

Context: A major portion of Kashmir's famous Dal Lake and several other water bodies froze on as the cold wave in the valley continued with Srinagar recording the coldest night in 30 years.

'Chillai-Kalan'

• Kashmir is currently under the grip of 'Chillai-Kalan' — the 40-day harshest winter period when a cold wave grips the region and the temperature drops considerably leading to the freezing of water bodies including the famous Dal Lake here as well as the water supply lines in several parts of the valley.
• The chances of snowfall are the most frequent and maximum during this period and most areas, especially in the higher reaches, receive heavy snowfall.
• While 'Chillai-Kalan' — which began on December 21 — will end on January 31, the cold wave continues even after that in Kashmir with a 20-day-long 'Chillai-Khurd' (small cold) and a 10-day-long 'Chillai-Bachha' (baby cold)

Dal Lake:

• It is a lake in Srinagar, the summer capital of Jammu and Kashmir, India.
• It is an urban lake, which is the second largest in the union territory of Jammu and Kashmir.
• It is integral to tourism and recreation in Kashmir and is named the "Lake of Flowers", "Jewel in the crown of Kashmir"or "Srinagar's Jewel".
• The lake is also an important source for commercial operations in fishing and water plant harvesting.
• The floating gardens, known as "Rad" in Kashmiri, blossom with lotus flowers during July and August.
• Dal is mentioned as Mahasarit in ancient Sanskrit texts.

https://www.thehindu.com/news/national/other-states/dal-lake-partially-freezes-srinagar-records-coldest-night-in-30-years/article33574017.ece